Intel Core i7-7700K ("Kaby Lake") Review and Ratings

Editors’ Rating:

Our Verdict:
Intel's "Kaby Lake" Core i7 flagship is speedy, with hardware support for 4K streaming and HDR for services like Netflix. But performance gains over its previous-generation counterpart are fairly minimal, and our review chip didn't have much overclocking headroom. Read More…

Intel Core i7-7700K ("Kaby Lake") Review

Table of Contents

Introduction, Chipset Background & Features

We knew going into Intel's latest 7th-Generation Core desktop processor lineup that raw performance gains weren't going to be all that substantial.

After all, the company announced in early 2016 that its longstanding "tick-tock" approach to processor development was ending. The notion of releasing a chip line first based on an efficiency-focused process-node shrink and an existing architecture (a tick), followed by a move to a brand-new architecture line (tock) on that now well-tested smaller manufacturing process (followed by another tick, then another tock, etc.), served Intel well for almost a decade. But as transistor sizes became increasingly microscopic, Intel announced that it would shift to a three-step process the company is calling "process, architecture, optimization."

We saw the initial shift to a 14-nanometer (nm) process with 5th-Generation "Broadwell" chips like the Core i7-5775C in late 2014 and early 2015. Then Intel released a new architecture built on the same 14nm with its "Skylake" chips like the Core i7-6700K the following year. And in the second half of 2016, Intel launched mobile versions of its 7th-Generation Core "Kaby Lake" processors, built on an optimized version of the 14nm process, but effectively the same architecture as Skylake. That optimization allows for some higher clock speeds, and Intel added some additional hardware for efficiently decoding 4K video. But in general, these mobile 7th-Generation chips delivered a roughly 10 to 12 percent performance boost over the 6th-Generation parts they were replacing, mostly due to the increased clock speeds. Many systems with these chips also delivered improved battery life, but much of that seems to be down to system makers including slightly larger batteries in many revamped machines that featured these new CPUs.

Now Intel is taking the wraps off its 7th-Generation Kaby Lake desktop processors, including the Core i7-7700K we're looking at here. These chips feature the same hardware decoding engine for 4K streaming from services like Netflix and other streaming providers that was packed into the mobile processors in the same Kaby Lake family. And Intel has managed to raise the base clock of this Core i7 chip to 4.2GHz, compared to the 4GHz base clock of the Core i7-6700K it's supplanting. That helps propel the Core i7-7700K to new performance levels for this class of processors. But that performance is more or less in line with the low-double-digit percent gains we saw in mobile 7th-Generation chips. In other words, if you have a high-end Skylake chip, or even a Broadwell or Haswell i7, there may not be a compelling reason to upgrade—at least right away.

But what about overclocking, and the new 200-series chipsets that roll out with these processors as well? For that, we'll need to delve a little deeper. We'll do that in the next section, as well as get into one of the 7th-Generation lineup's most intriguing new features: support for Intel's upcoming XPoint-based Optane memory, which is expected to hit the market sometime in the first half of 2017.

Features & Other New Chips

It would be an understatement to say that Intel is dropping a whole lot of 7th-Generation chips alongside the Core i7-7700K. By our count, looking at the company's press materials, the total number of 7th-Generation chips available with the brand-new releases (including the flagship desktop chip we're discussing here and the previous U- and Y-Series mobile parts that launched in the fall of 2016) is 42. You won't find the answer to the ultimate question of life, the universe, and everything in that number. But you will find plenty of new mobile chips, including several business-focused models with support for things like vPro and more secure biometrics, as well as a whole lineup of H-Series quad-core chips that are most often found in gaming laptops and mobile workstations.

But of course we're here to talk about desktop processors, and 16 of the new chips are of that variety. The good news is that these CPUs use the LGA 1151 socket, so they should be drop-in compatible with many previous-generation (Skylake) motherboards, although you'll probably need to install a BIOS update first.

Rather than rattle off all 16 new chips and their specs, here's a list of the new desktop SKUs and their specs, direct from Intel.

Note that, at a 91-watt TDP (thermal design power, a measure of required heat dissipation), the Core i7-7700K we're looking at here matches that of the Core i7-6700K, its counterpart in the previous 6th-Generation lineup. Considering the architecture is fundamentally the same and clock speeds aren't all that different, that's expected. In fact, the specs between this chip and the one it's designed to replace are so similar that we only had to change a few digits when writing up the specs of the new model compared to the 6th-Generation i7-6700K.

Essentially, compared to the Core i7-6700K, Intel boosted the base clock from 4GHz to 4.2GHz with the new chip, and upped the top Turbo Boost frequency at stock speeds from 4.2GHz to 4.5GHz. The integrated graphics chip gets a boost in name from HD Graphics 530 on the previous chip to HD Graphics 630 on the newer models, but the 1,150MHz dynamic frequency remains the same. And an Intel rep told us that aside from the new media engine for HEVC 10-bit content (the chosen codec for streaming 4K content from the likes of Netflix, Amazon, and likely soon-to-be other providers), the graphics core here is fundamentally the same. That's interesting, because as we'll see in testing, we did notice some performance improvements on the graphics front. But that may solely be down to higher supported RAM speeds (which we'll detail shortly in the chipset section coming up).

The most interesting chip in Intel's new desktop lineup seems to be the Core i3-7350K. The company's first unlocked Core i3 CPU, it's a dual-core, four-thread chip with the same 4.2GHz base clock speed (it has no Turbo Boost) as the i7 chip we're looking at here. It looks to be a strong candidate for a budget-friendly gaming chip, and a good general-use part for those who don't often do things like render massive video files (which will take full advantage of the four cores and eight threads of the i7), as well. In fact, with its high base clock speed and much lower price, it has the potential to steal a fair bit of thunder from Intel's costlier chips, as it should be just as quick for most general computing tasks. The Core i3-7350K is listed at $168, while the Core i7-7700K we're reviewing here lists at $339. These are prices for chips in 1,000-unit lots, but unless there are shortages (which there were for a while when the Core i7-6700K and Core i5-6600K launched), street prices tend to generally hover close to Intel's "1ku" pricing for at least a few months after launch.

We'll have to wait to see how the unlocked Core i3 chip fares for a future date, however. The only 7th-Generation chip we have to test today is the top-end Kaby Lake part, the Core i7-7700K. Before we get to that, though, let's detail the new Z270 chipset, and figure out just what Intel's Optane memory is.

Z270 Chipset Details

Just as it has with previous chip generations, Intel is outing a handful of new chipsets alongside its 7th-Generation desktop processors, including H270 and H250 for mainstream systems, and B250 for business machines. But we'll be focusing on Z270 here, as that's the top-end chipset, aimed at enthusiasts and overclockers, and so the one best paired with a high-end chip like the Core i7-7700K.

There's no getting around the fact that, much the way the 7th-Generation processors are a refined but very similar update over their 6th-Generation counterparts, Z270 has a whole lot in common with the Z170 chipset it's succeeding. Intel's press material on the new chipset is just five pages long, and about three of those pages are taken up by photos of young people doing things like singing in a studio and assembling a scientific model in front of a laptop.

Here's a diagram of the Z270 chipset, direct from Intel.

Again, looking at the same diagram for the Z170 chipset, most of what's here is the same. The fundamental changes include four additional PCI Express (PCIe) 3.0 lanes. But they're hanging off the chipset, not directly connected to the CPU, so they aren't meant for extra graphics cards. That's becoming increasingly unnecessary, anyway, as Nvidia has limited its latest high-end cards (the GeForce GTX 1080 and GTX 1070) to just two cards in SLI. Also, the DMI 3.0 interlink between the chipset and the CPU itself is the same bandwidth-limiting connection as in the Z170 chipset, so the pipe connecting the chipset to the processor isn't any wider or faster.

That means you can think of the Z270's extra four lanes like additional "plugs" in a power strip, in that they let you add more devices, but the level of voltage and current from the wall is the same. The lanes will allow you to install more bandwidth-hungry devices, say fast PCIe/NVMe solid-state drives (SSDs) like Samsung's excellent SSD 960 EVO. The Z270 chipset does support three-way PCIe RAID SSD setups (as Z170 did). And we're starting to see more and more of these kinds of drives, as well as Thunderbolt 3 external devices like monitors, which can also eat up lots of bandwidth. So having the ability to plug more things into the PCIe pipe is definitely a good thing. But just as we saw in previous-generation boards, installing some device types will likely then disable others, as there's still a limited amount of data that can travel between the CPU and the chipset (and vice versa) in a given time period.

Another change with Z270 is a bump up in officially supported RAM speeds, from 2,133MHz with Z170 to 2,400MHz here. That's nice, as higher memory speeds can make a big difference for integrated graphics performance. But RAM makers have long blown past Intel's officially supported RAM speeds. The Corsair DDR4 set we used for our Skylake testbed was rated to run at 3,000MHz (and ran at that speed without issue), and G.Skill sent us a 16GB TridentZ kit for testing Intel's new chips that ran at 3,600MHz after ticking on an XMP profile with a couple of clicks in the BIOS. So Intel's officially rated RAM speeds are of little importance to system builders. They may, though, result in faster RAM for big-box desktops and all-in-ones, as those types of systems are more likely to stick with officially supported settings.

The last major addition of the Z270 chipset, in tandem with the new 7th-Generation processors, is support for Intel's upcoming Optane memory, which the company says will arrive sometime in the first half of 2017. Now, the frustrating thing is that the details about Optane memory are still scarce. Intel tells us it will be based on the same 3D XPoint (pronounced "cross point") technology as its promised upcoming XPoint-based SSDs. Basically, the promise behind XPoint is that it will be able to provide speeds and extremely low latency similar to RAM, with capacities like those of SSDs, all with the non-volatile nature that we're used to from storage drives—meaning data won't be lost if the power is interrupted, as is the case with RAM. But Intel says that Optane memory is distinct from Optane SSDs, and that the former will be used as an extremely fast cache for hard drives (and presumably SSDs). This sounds much like how solid-state cache was used commonly in systems a few years back, to make hard drives more responsive in the days when SSDs were too expensive, or the way SSD caches are still used in hybrid hard drives.

This all sounds promising, but as of this writing, it's unclear what physical form Optane memory will take (though it has been announced as short M.2 drives in some upcoming Lenovo ThinkPads), how much it will cost, or how much real-world advantage users will see compared to just using traditional SSDs, which are becoming increasingly affordable. After all, excellent budget SSDs like the Crucial MX300 are selling for less than $130 for a 525GB model. So Optane memory would have to be extremely inexpensive or very impressive (or both) to find broad uptake from enthusiasts, particularly in the desktop space.

We have no doubt that Optane memory will provide a huge boost in the snappiness of a system that's running off of a traditional hard drive, but the enthusiasts who are most likely to buy into new technology like Optane early on are less likely to be building a new system based solely around a spinning drive for storage. And even lightning-quick NVMe SSDs like the aforementioned Samsung 960 EVO or Intel's own 750 Series SSD, while they deliver much faster performance in benchmarks and when reading or writing several gigabytes of files, don't feel any faster than a good SATA SSD in general use.

In other words, Optane memory support sounds good, and it's great to have future-looking features on board (pun intended) when you're building a new PC. But we'll have to wait and see how this new technology manifests before deciding whether or not support for it is a major selling point. Interestingly, Intel was quick to point out that both a 7th-Generation CPU and a 200-series motherboard are a requirement for Optane memory, meaning you can't install it in a previous-generation Z170 motherboard, even with a Core brand-new i7-7700K processor in the socket. But when pressed, Intel representatives would not say the same about support for Optane SSDs. And really, for enthusiasts, Optane drives sound much more appealing that Optane caching tech. We'll just have to wait to see how this plays out as 2017 progresses.